The invention relates to plant husbandry, but more particularly, the invention relates to plant covers of the type that protect plants from damage caused by climatic temperature conditions.
It is desirable to plant seeds or seedlings of certain agricultural crops as early as possible in a growing season. Early planting may be directed toward the following goals: (1) planting more than one crop during a growing season; (2) assuring full maturity of a crop; or (3) early marketing of a crop.
In some locals, daytime temperatures may be high enough to sustain plant growth but temperatures during the night or a few days may be cool enough to damage the plants or curtail their growth.
It was early recognized that a plant protector or cover having a thermally responsive venting means is advantageous. Such a plant protector is disclosed by U.S. Pat. 585,009 as issued to Taylor et al. However, devices such as Taylor's are unsatisfactory and too expensive for present day agricultural needs. The devices are also unsatisfactory when taken in view of improved thermally responsive actuators such as disclosed by U.S. Pat. No. 2,489,879 as issued to Grebe.
To meet present day growing needs, it is common practice in many agricultural areas to cover a row of plants with a tent-like structure of wooden stakes, wire, and pliable, light-transparent material. The structure or "plant cover" must be manually attended to assure a tolerable or stimulating environment for the plants. During daylight hours, the plant cover may be manually vented by partial disassembly. Venting protects the plants from damaging high temperatures that could develop underneath the plant cover. The plants must be manually recovered to protect them from harmfully cold night or day temperatures. This invention is directed toward overcoming the manual operation of present-day plant covers.